An Afghan election commission worker sort ballots for an audit of the presidential run-off votes at an election commission office in Kabul, Afghanistan, Monday, Aug. 25, 2014. Afghanistan’s president Hamid Karzai said in a statement that the inauguration ceremony for the next country’s president will be held on September 2, 2014 and it is not subject to change. (AP Photo/Rahmat Gul

Afghan election commission workers sort ballots for an audit of the presidential run-off votes at an election commission office in Kabul, Afghanistan, Monday, Aug. 25, 2014. Afghanistan’s president Hamid Karzai said in a statement that the inauguration ceremony for the next country’s president will be held on September 2, 2014 and it is not subject to change. (AP Photo/Rahmat Gul)

Afghan election commission workers sort ballots for an audit of the presidential run-off votes at an election commission office in Kabul, Afghanistan, Monday, Aug. 25, 2014. Afghanistan’s president Hamid Karzai said in a statement that the inauguration ceremony for the next country’s president will be held on September 2, 2014 and it is not subject to change. (AP Photo/Rahmat Gul)

An Afghan election worker carries a box of presidential run-off ballots for the audit process at an election commission office in Kabul, Afghanistan, Monday, Aug. 25, 2014. Afghanistan’s president Hamid Karzai said in a statement that the inauguration ceremony for the next country’s president will be held on September 2, 2014 and it is not subject to change. (AP Photo/Rahmat Gul

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KABUL, Afghanistan (AP) — One of the two men vying to become Afghanistan’s next president is threatening to boycott a ballot audit from the country’s disputed presidential runoff, his adviser said Tuesday, a development that could further disrupt the already troubled process.

The complicated, U.N.-supervised audit of the 8 million votes from the June presidential runoff has been underway in Kabul for weeks.

The process followed allegations of vote fraud on both sides and is meant to decide whether Abdullah Abdullah, a former foreign minister, or former Finance Minister Ashraf Ghani Ahmadzai will replace President Hamid Karzai.

Abdullah is apparently concerned that the audit has allegedly failed to invalidate a sufficient number of ballots so far that would correspond to the level of vote fraud his team claims has taken place.

A top adviser for Abdullah told reporters on Tuesday that if Abdullah’s concerns are not addressed by Wednesday morning, he will pull out of the audit.

“If our demands are not accepted, we will announce the end of this process,” said Fazel Ahmad Manawi. “This process will not be acceptable to us and the result will not have any value.”

Manawi said the election commission ignored their complaints about fraudulent ballots.

If the recount is halted, it would create another major political stalemate for Afghanistan. Karzai has said the new president should be sworn in on Sept. 2. Karzai’s successor is also expected to attend a NATO summit to be held next week.

The lack of new president has also held up the signing of a security agreement between the U.S. and Afghanistan. Both candidates have promised to sign the agreement, which Karzai rejected.

The audit has proceeded, with fits and starts, in warehouses on the edge of Kabul, where hundreds of workers of the Independent Election Commission have been pouring through roughly 23,000 ballot boxes from across the country. Their work has been monitored by U.N. as well as international observers and representatives of the opposing teams.

Observers from both Abdullah’s and Ahmadzai campaign teams have observed the process, sometimes arguing intensely over issues such as whether unfolded ballot papers should be thrown out or whether check marks on ballots are too similar, a possible indication of fraud.

On Monday, the election commission announced the first invalidations in the audit, saying results from 72 of the 3,645 polling stations it initially assessed have been completely invalidated. Nearly 700 more polling stations were partially invalidated.

There was no immediate information how the invalidations would affect the end result of the election.

But Mujib Rahman Rahimi, a spokesman for Abdullah, said Tuesday the low number of invalidations shows the audit “is not working.”